Method of maximizing anharmonic oscillations in deuterated alloys

ABSTRACT

For a condensed matter system containing a guest interstitial species such as hydrogen or its isotopes dissolved in the condensed matter host lattice, the invention provides tuning of the molecular orbital degeneracy of the host lattice to enhance the anharmonicity of the dissolved guest sublattice to achieve a large anharmonic displacement amplitude and a correspondingly small distance of closest approach of the guest nuclei. The tuned electron molecular orbital topology of the host lattice creates an energy state giving rise to degenerate sublattice orbitals related to the second nearest neighbors of the guest bonding orbitals. Thus, it is the nuclei of the guest sublattice that are set in anharmonic motion as a result of the orbital topology. This promotion of second nearest neighbor bonding between sublattice nuclei leads to enhanced interaction between nuclei of the sublattice. In the invention, a method for producing dynamic anharmonic oscillations of a condensed matter guest species dissolved in a condensed matter host lattice is provided. Host lattice surfaces are treated to provide surface features on at least a portion of the host lattice surfaces; the features have a radius of curvature less than 0.5 microns. Upon dissolution of the guest species in the treated host lattice in a ratio of at least 0.5, the guest species undergoes the dynamic anharmonic oscillations.

GOVERNMENT RIGHTS IN THE INVENTION

This invention was made with U.S. Government support under contract No.F19628-90-C-0002, awarded by the Force. The Government has certainrights in this invention.

FIELD OF THE INVENTION

This invention relates to techniques for enhancing conditions forcausing anharmonic oscillations in protonated and deuterated alloys,leading to enhanced electron tunneling between degenerate molecularorbitals and enhanced nuclei interaction; and more particularly relatesto materials processing techniques for maximizing anharmonicoscillations of hydrogen isotope nuclei in the interstices of suchalloys.

BACKGROUND OF THE INVENTION

Strong force nuclear interaction of hydrogen isotopes, deuterium inparticular, have been extensively studied in the regime above 30,000 eV.Tunneling phenomena through the Coulomb barrier has been wellcharacterized and described as requiring tunneling through a barrier of0.7 Å in width and 400,000 eV in height.

Interaction of nuclei in a palladium-deuterium condensed matter systemhas been shown to be 10⁷ times more probable than the Coulomb tunnelingdescribed above. The reposed successes in this system are best accountedfor by a palladium-deuterium interaction scheme occurring in thepresence of strong wave function overlap. It has been shown that suchwavefunction overlap may be achieved via specific molecular orbitaldegeneracy conditions.

Fundamental shifts in the molecular orbital topology of a condensedmatter system are known to be achievable via sub-micron,nanometrically-sized surface features. Such nanometric space featuresalter the surface and near surface electrochemistry of a condensedmatter system, and thereby effect the orbital topology of the system.This effect cannot be attributed to a simple increase in surface area;rather, the surface character at the nanoscale can only be predictedfrom a real-space molecular orbital perspective. The resultingproperties are purely quantum-mechanical in nature, i.e., they cannot bederived by a simple extension of continuum elasticity theory to thenanoregime. Thus, nanometric, low-dimensional surface features can beexpected to interact with electromagnetic fields and radiation in acorresponding quantum-mechanical nature.

SUMMARY OF THE INVENTION

In view of the above considerations, the inventors herein haverecognized that for a condensed matter system containing a guestinterstitial species such as hydrogen or its isotopes dissolved in thecondensed matter host lattice, tuning of the molecular orbitaldegeneracy of the host lattice via the methods of the invention enhancesthe anharmonicity of the dissolved guest sublattice to achieve a largeanharmonic displacement amplitude and a correspondingly small distanceof closest approach of the guest nuclei. The electron molecular orbitaltopology of the host lattice creates an energy state giving rise todegenerate sublattice orbitals related to the second nearest neighborsof the guest bonding orbitals. Thus, it is the nuclei of the guestsublattice that are set in anharmonic motion as a result of the orbitaltopology.

The invention provides methods for enhancing this guest latticeanharmonicity such that promotion of second nearest neighbor bondingbetween sublattice nuclei leads to enhanced interaction between nucleiof the sublattice.

In one aspect, the invention provides a method for producing dynamicanharmonic oscillations of a condensed matter guest species dissolved ina condensed matter host lattice. In the method, host lattice surfacesare treated to provide surface features on at least a portion of thehost lattice surfaces; the features have a radius of curvature less than0.5 microns. Thereupon dissolution of the guest species in the hostlattice in a ratio of at least 0.5, the guest species undergoes thedynamic anharmonic oscillations.

In preferred embodiments, the host lattice comprises palladium, apalladium silver alloy, preferably Pd.sub..77 Ag.sub..23, or nickel. Theguest species comprises hydrogen or deuterium. Preferably, the surfacefeatures of the host lattice have a radius of curvature less than 0.3microns, and more preferably, less than 0.2 microns. The guest speciesis dissolved in the host lattice preferably in a ratio of at least 0.8.In prefer, red embodiments, the dynamic oscillations are characterizedby an oscillation amplitude of at least 0.5 Å and an oscillationfrequency of at least 10¹⁰ Hz. Preferably, the dynamic oscillations aresustained over time such that interaction of guest species nuclei isinitiated and maintained over time.

In other preferred embodiments the host lattice comprises a sheet ofpalladium silver alloy, preferably wound to form a coiled tube of thesheet. The gust species dissolution is preferably accomplished bysubmerging the host lattice is an electrolytic solution of the guestspecies. A platinum-coated anode is submerged in the solution and avoltage is applied between the host lattice and the anode; preferablythe voltage is a square wave signal having a DC offset voltage, wherethe signal is characterized by a time varying amplitude no less than0.93 volts and a frequency between about 5 Hz and 2000 Hz.

In other preferred embodiments, a host lattice is provided by acontinuous wire that is drawn through a diamond die which has beenprocessed to include relief structures on inner surfaces, the reliefstructures having a radius of curvature less than 0.5 microns.Preferably, the wire is a continuous nickel wire or a multiclad wireconsisting of a nickel core surrounded by a layer of palladium, and theinner surfaces of the die result from laser processing of the innersurfaces.

In other preferred embodiments, the host lattic surface is treated bylapping the surface using a polishing slurry or scribing the surfacewith a diamond stylus. Preferably, the diamond stylus has a working tipdiameter less than 0.5 microns; more preferably the scribing isaccomplished using an array of tips all positioned on a common stylusfixture, and after the scribing, the surface is anodically etched with ahydrochloric acid solution undergoing ultrasonic agitation.

In other preferred embodiments, the lattice surface is treated by anodicetching of the surface, or chemical vapor deposition or molecular beamepitaxy of host lattice material on a substrate. Preferably, the hostlattice surface is treated by lithographically defining a pattern ofsurface features on at least one surface and etching the patternedsurface to produce the surface features. Preferably, the patternedsurface is anodically etched, and the etching results in V-shapedsurface grooves, rectangular-shaped surface channels, or prismaticasperities.

In another aspect, the invention provides apparatus for producingdynamic anharmonic oscillations of a condensed matter guest species. Theapparatus includes a condensed matter host lattice having surfacefeatures of a radius of curvature less than 0.5 microns on at least aportion of its surfaces, and apparatus of dissolving the guest speciesin the host lattice in a ratio of at least 0.5, the guest speciesundergoing the oscillations upon dissolution in the host lattice.

In preferred embodiments, the guest species is provided in anelectrolytic solution of the guest species; the electrolytic solution ispreferably a solution of heavy or light water and K₂ CO₃.

In another aspect the invention provides a host lattice for causing aguest species dissolved in the host lattice to undergo dynamicanharmonic oscillations according to the methods of the invention.Preferably, the host lattice comprises a coiled tube formed of a sheetof palladium silver alloy. In other preferred embodiments, the hostlattice comprises a superlattice of first and second submaterialsalternately layered in layers of between 10 and 100 nanometers inthickness. Preferably, the host lattice submaterials are nickel andcopper, or nickel and palladium, or copper and palladium. In otherpreferred embodiments, the host lattice structure has been cold worked,and comprises a nanograined polycrystalline morphology.

Other features and advantages of the invention will be apparent from thedescription of a preferred embodiment, and from the claims.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a rendering of a conventional X-ray photo-spectroscopy plot ofX-ray intensity as a function of molecular orbital energy for ahypothetical condensed matter sample;

FIG. 2A is a plot of the Jahn-Teller coupling parameter β as a functionof the percent bond overlap of electron molecular orbitals of secondnearest neighbor hydrogen atoms near the Fermi energy;

FIG. 2B is a plot of nuclear displacement oscillation amplitude as afunction of the Jahn-Teller coupling parameter β;

FIGS. 3A-3D illustrate the steps of producing a palladium-nickel cladwire according to one aspect of the invention;

FIGS. 4A-4F illustrate the steps of a first method for lithographicallydefining nanoscopic surface features according to another aspect of theinvention;

FIGS. 5A-5F illustrate the steps of a second method for lithographicallydefining nanoscopic surface features according to another aspect of theinvention;

FIG. 6 schematically illustrates a cell activation and measurementset-up according to one aspect of the invention;

FIG. 7 schematically illustrates the activation cell of FIG. 6 in moredetail; and

FIG. 8 schematically illustrates the anode of FIG. 7 in more detail.

DESCRIPTION OF A PREFERRED EMBODIMENT

We first present a discussion of anharmonicity in condensed matter.Referring to FIG. 1, there is shown a conventional X-rayphoto-spectroscopy plot of X-ray intensity (horizontal axis) as afunction of molecular orbital energy (vertical axis) for a hypotheticalcondensed matter sample. The vertical axis also depicts specificmolecular orbital energy levels for the sample. Beginning with theorbital of lowest energy, some number of molecular orbitals of thesample are fully occupied, up to an energy level above which themolecular orbitals are unoccupied. The fully occupied orbitals are eachassociated with a specific symmetry and steric state. The Fermi energy,E_(f), is defined as that energy level halfway between the energy levelof the highest occupied molecular orbital (HOMO) and that of the lowestunoccupied molecular orbital (LUMO). The energy gap, ΔE, is defined asthe energy difference between the energy levels of the HOMO and LUMO.

As the temperature of a sample is increased or radiation is applied tothe sample, the population of the HOMO shifts toward the LUMO, and themean energy of the molecular orbitals shifts a corresponding amount.Under certain arrangements of matter, the HOMO and LUMO can actuallyco-exist at the same energy level. This condition is referred to asorbital degeneracy. Under degenerate molecular orbital conditions,condensed matter systems generally find it energetically favorable tolower the free energy of the system by dynamically distorting, or inextreme cases, statically distorting to a state of symmetry lower thanits existing symmetry state. An example of such a distortion is a cubicmaterial undergoing a trigonal lattice distortion.

This static distortion is one embodiment of the well-known Jahn-Tellereffect, relating to condensed matter distortion. According to theJahn-Teller effect, when electron molecular orbital degeneracyconditions are achieved, both static distortions and dynamic distortionsare possible and both result in an energetically more favorable state.Of great importance is the fact that under dynamically degenerateconditions the electrons in the degenerate molecular orbitals can tunnelback and forth in space between degenerate orbitals, centered onseparate atoms, at very high rates, where the tunneling rate is denotedas ω_(c). The amplitudes of these tunneling oscillations are undercertain conditions so large that the positive nuclei of the parent atomsto the tunneling electrons respond to the oscillations in some fashion,i.e., the electron oscillations may couple to the parent nuclei lattice.In this case, the amplitude of the oscillations of the parent nuclei, inresponse to the electron tunneling oscillations, is termed δ.

Referring to FIG. 2A, the Jahn-Teller coupling parameter, β,characterizes the degree of degeneracy of a particular molecular orbitalenergy configuration, and correlates that degree to a measure of theelectronic molecular orbital overlap of the configuration. The couplingparameter β has a range between 0 and 1/2. For a condensed matterlattice characterized by β=1/2, the lattice is not experiencingJahn-Teller tunneling oscillations, but rather, oscillations arecharacterized as thermal parabolic oscillations expected of harmonicoscillation behavior. As the local bonding arrangements of the condensedlattice are shifted towards degeneracy, the β parameter decreases below1/2, and the overlap of molecular orbitals increases. The tunnelingoscillations of electrons in the degenerate molecular orbitals becomeless and less harmonic in character. This type of tunneling oscillationis referred to as anharmonic oscillation because the oscillations arederived from statistical fluctuations in molecular orbital occupancy andare nearly insensitive to temperature, unlike harmonic oscillations,which are thermal in nature. In general, systems characterized by a βparameter less than about 1/4 become so structurally unstable duringdynamic tunneling oscillations that they statically distort to a lowersymmetry and settle into a new harmonic condition, like the cubic totrigonal distortion mentioned above.

A method for predicting the molecular orbital overlap resulting from agiven orbital degeneracy is given in"Hydrogen-hydrogen/deuterium-deuterium bonding in palladium and thesuperconducting/electrochemical properties of PdH_(x) PdD_(x)," by Dr.Keith Johnson, et al, Modern Physics Letters B, Vol. 3, no. 10, pp.795-803, July 1989, and is herein incorporated by reference. Based onthis orbital overlap prediction technique, which provides a method forquantizing the Jahn-Teller coupling parameter, β, the orbital degeneracyof a condensed lattice system may be selectively "tuned", or specified,to provide a desired degree of molecular orbital overlap. By tuning thedegeneracy of the system to, e.g., increase the system degeneracy, the βcoupling parameter characterizing the material is in turn (orinherently) decreased.

Referring again to FIG. 1, as the degeneracy of a condensed mattersystem is tuned so that the HOMO and LUMO come closer together, theenergy gap, ΔE, between the HOMO and LUMO approaches zero. The magnitudeof this energy gap is directly related to the rate of molecular orbitalelectron tunneling, T_(R), by:

    T.sub.R =Ae.sup.-ΔE/KT                               (1)

where:

K is the Boltzmann constant

T is degrees Kelvin.

From this relationship (1) it is clear that as the energy gap betweenthe HOMO and LUMO approaches zero, the electron tunneling rate T_(R)correspondingly increases.

At high tunneling rates, the tunneling electrons impart theiroscillatory motion to the corresponding parent nuclei; the nuclei areeffectively "dragged" through the anharmonic oscillatory motion of thetunneling electrons. Thus, the corresponding rate of anharmonic nucleioscillation, is also, as expected, related to the degree of molecularorbital overlap, via the coupling parameter β. The frequency of nucleioscillations, ω_(c), in terms of the coupling parameter, is given as:

    ω.sub.c =h(m.sub.e /M.sub.i).sup.β /2m.sub.e d.sup.2 (2)

where:

m_(e) =mass of electron

M_(i) =mass of parent nuclei

β=Jahn-Teller coupling parameter (quantified based on the orbitaloverlap-degeneracy prediction model)

d=separation between second nearest neighbor nuclei (the correlationdistance between molecular orbitals of opposite phase, Ψ⁺ and Ψ⁻ (notthe lattice parameter))

h=Plank's constant.

Referring to FIG. 2B, the amplitude of parent nuclei oscillation, δ,resulting from the degree of anharmonicity caused by orbital overlap, asgiven by the coupling parameter β, mathematically ranges between 0-1.7Å, for β ranging between 0-0.5, although, as explained above, β valuesdose to zero are physically meaningless. The details of bonding overlap,however, restrict the value of β to above 0.1. Thus, referring also toFIG. 2A, a measure of the coupling parameter β provides a means forcorrelating a degree of molecular orbital overlap, or degeneracy, to theamplitude of nuclear displacement resulting from anharmonic oscillationsof electrons in the degenerate molecular orbitals. The relationshipnuclear displacement amplitude, δ, to the Jahn-Teller couplingparameter, β, is quantified as:

    δ=(m.sub.e /M.sub.i).sup.β d.                   (3)

Based on this relationship, as illustrated in FIG. 2B, it is seen thatas β decreases from 0.5 toward 0.1 (becoming more degenerate) the parentnuclei (e.g., deuteron) displacement amplitude δ increases to over 10times the amplitude associated with thermal (harmonic) oscillations. Infact, the parent nuclei displacement amplitude may realisticallyapproach or exceed 0.6 Å.

The average distance of closest approach of adjacent parent nuclei whichare anharmonically oscillating is determined based on the displacementamplitude δ, described above, and the interstitial site distance betweentwo such oscillating nuclei. With this interstitial distance between thenuclei, or bond separation parameter, given as d, the average distanceof closest approach for adjacent anharmonically oscillating nuclei isgiven as d-2δ. This distance may be equivalently considered as theaverage distance of penetration into the coulomb barrier achieved byadjacent oscillating nuclei.

The inventors herein have recognized that the probability forinteraction of neighboring nuclei may be dramatically increased viaenhancement of the anharmonic nuclei oscillation phenomenon discussedabove, and further that this anharmonic oscillation may be "tuned" byspecifying a particular molecular orbital degeneracy (and correspondingelectron orbital tunneling) via a corresponding degree of molecularorbital overlap. Both the anharmonic oscillation nuclei displacementamplitude, δ, and the frequency of anharmonic oscillation, ω_(c), wereshown above to be strongly dependent on β, the Jahn-Teller couplingparameter, which provides a measure of the molecular orbital overlap, ordegeneracy, for a given system. The probability for two nuclei tointeract will be shown below to be strongly dependent on the distance ofclosest approach between any two nuclei, given above as d-2δ, and thefrequency at which this closest approach occurs. The coupling parameterβ thus provides a mechanism for correlating a given state of molecularorbital degeneracy with a probability of nuclei interaction. To achievea maximum probability for interstitial nuclei interaction, then, amolecular orbital degeneracy state is selected which, for a givencondensed matter system, minimizes the distance of closest approach ofnuclei during oscillations while at the same time maximizing thefrequency of those oscillations.

For a condensed matter system containing hydrogen, deuterium, tritium,or other interstitial species dissolved in a host lattice, the inventorsherein have recognized that by "tuning" the molecular orbital degeneracyof the host lattice, the anharmonicity of the dissolved hydrogen ordeuterium nuclei sublattice residing in the host lattice may be enhancedto achieve the conditions described above, i.e., a large displacementamplitude, δ, of the hydrogen or deuterium nuclei and a correspondinglysmall distance of closest approach, and a high oscillation frequency ofdeuterium or hydrogen nuclei. It must be emphasized that it is theelectron molecular orbital topology of the host lattice that creates anenergy state giving rise to degenerate sublattice orbitals related tothe second nearest neighbors of, e.g., H--H guest bonding orbitals.Thus, it is the nuclei of the guest sublattice that are set inanharmonic motion as a result of the orbital topology.

The invention herein provides methods for enhancing this sublatticeanharmonicity via "tuning" of the host lattice molecular orbitaldegeneracy. These methods, described below, all provide common results:they act to promote second nearest neighbor bonding between sublatticenuclei; and they thereby promote maximization of the anharmonicoscillation amplitude and oscillation frequency of the sublatticenuclei.

A variety of metal alloys have been investigated to determine thatalloy, which by the nature of its molecular orbital degeneracy,maximizes anharmonic oscillations of deuterium or hydrogen dissolved inthe alloy lattice. The molecular orbital overlap, corresponding couplingparameter β, and anharmonicity of deuterated palladium alloyed withlead, bismuth, titanium, silver, copper, zirconium, germanium, silicon,aluminum, thallium, and gold has been investigated, as well asdeuterated nickel alloyed with titanium. "Deuterated" is here defined toinclude any of the three hydrogen isotopes deuterium, tritium, andprotons. All of the investigated alloys possess tetrahedral andoctahedral interstitial sites, yet not all of the alloys serve toenhance the molecular orbital degeneracy of interstitial guest species.Based on an analysis of the degree of molecular orbital degeneracy ofeach of the palladium alloys, palladium silver is the preferred alloy,as it maximizes hydrogen isotope anharmonicity.

In pure palladium and palladium alloys, the lattice parameter, a, of thepalladium atoms in the lattice ≈3.6 Å. The space in the palladiumlattice may be populated by a guest species, e.g., introduction ofdeuterium nuclei dissolved in the lattice to occupy octahedral andtetrahedral interstitial locations of the lattice, via electrolyticcharging. After this charging, the deuterium nuclei constitute secondnearest neighbors (with each other) in a degenerate orbital condition.Deuterium is the preferred guest nuclei species, but hydrogen is also anacceptable guest species.

While the separation between second nearest neighbor deuterium nucleilocated at octahedral interstitial sites within the host lattice is 3.6Å, the same length as the palladium lattice parameter, once electrolyticcharging of deuterium reaches a high level, the deuterium nuclei beginto populate the smaller tetrahedral interstitial sites of palladium andits alloys, and the distance between a neighboring interstitialtetrahedral and octahedral site is 1.7 Å, less than one-half the latticeparameter distance. Thus, deuterium nuclei populating adjacentoctahedral and tetrahedral sites are closer together, and have a higherspatial density, than nuclei populating only octahedral sites.

This small equilibrium distance between tetrahedral and octahedral siteddeuterium nuclei, in combination with enhanced anharmonic oscillationsof those nuclei, create the conditions necessary for enhancedinteraction between the deuterium nuclei.

Of the metal alloys investigated, it is found that palladium silverprovides the highest degree of guest deuterium nuclei anharmonicity.This silver compound increases the dΔ-sσ, antibonding component of thepalladium-deuterium molecular orbitals, at concentrations up to about23% silver, thereby promoting more overlap of the second nearestneighbor D--D(sσ) bonding molecular orbitals and providing an enhancedmolecular orbital degeneracy. A particular deuterated palladium silvercompound, Pd.sub..77 Ag.sub..23 D, is preferred for a bulk alloyembodiment, but other palladium silver compounds, as well as other metalcompounds such as Au--Ni, Cu--Pd, Cu--Ni, Ni--Pd, Cu--Ni, Ni--Ti, Zr--P,Pd--P, Ni--Zr, Zr--Pd, and Zr--Ti also provide a degree of anharmonicitysufficient to enhance interaction of deuterium nuclei in the alloylattice. Thus, while the following discussion focuses on palladiumsilver, it must be recognized that other alloy compounds are alsosuitable.

Using the molecular orbital overlap modeling technique of Johnsondescribed above, the computed bond overlap of Pd.sub..77 Ag.sub..23 D(near the Fermi level) is calculated to be 35%. Using the graphicalrelationships in FIGS. 2A and 2B, this bond overlap correlates to aJahn-Teller coupling parameter β of 0.13, and a deuterium nucleianharmonic oscillation amplitude, δ, equal to 0.6. Then, using therelationship (d-2δ), given above, for determining the average distanceof closest approach for anharmonically oscillating deuterons in thepalladium ahoy lattice, with the bond separation parameter, d, being 1.7Å between an octahedral and tetrahedral deuterium nuclei, the averagedistance of closest approach of a D--D nuclei pair is 0.5 Å. Thisdistance is closer than even the bond distance in deuterium gas, whichis 0.7 Å. The average distance of closest approach must be reduced below0.5 Å to observe any strong force interactions at a rate above theexpected background rate. Thus, the probability, or expectation value,of finding an anharmonically oscillating deuteron pair inside the strongforce envelope is dramatically enhanced by small reductions in thisdistance of closest approach to reduce this distance below 0.5 Å.

Specific details of the energy potential between the deuterium atoms inthis anharmonic system are unknown. However, a semi-qualitative analysismay be performed using an expression derived by Sichlen and Jones forthe rate, R, of D--D nuclei interaction, using a Morse potential, asfollows:

    R=Ae.sup.(-λ(r.sub.d))                              (4)

where

A=the nuclei interaction attempt rate

λ(r_(d))=the reaction distance

(r_(d))=the Coulomb barrier penetration factor.

Factoring out the barrier width, such that λ(r_(d))=[(d-2δ)-λ'(r_(d))]and using (d-2δ)=1.05 and λ(r_(d))=180 for a D₂ molecule, and setting Aequal to the anharmonic oscillation frequency, ω_(c) the interactionrate of deuterium nuclei in a deuterium molecule is 10⁻⁷⁰interactions/D--D pair/sec, at room temperature.

Using the substitutions given above for the palladium system at roomtemperature, the equation is correlated to a PdD system given by:

    R=ω.sub.c e.sup.-(d-2δ)171.                    (5)

Substituting the values of (d-2δ) as 1.05 Å for the system of PdD, adeuterium nuclei interaction rate of 10⁻⁵⁰ is indicated. In contrast,substituting 5×10¹¹ rad/sec and 0.5 Å for the values of ω_(c) and(d-2δ), respectively, computed for the system of Pd.sub..77 Ag.sub..23D, indicates a deuterium nuclei interaction rate of 7×10⁻²⁷interactions/D--D pair/sec under the enhanced anharmonic conditions setup by the Pd.sub..77 Ag.sub..23 host lattice. Based on this analysis, itis clear that deuterium nuclei interaction is significantly promoted byanharmonic oscillation conditions.

The nature of the strong force nuclei interaction having a ratequantified by the above equation is not here specified; rather, thechemical and physical conditions that amplify the probability for theoccurrence of this strong force interaction are provided by the enhancedanharmonicity system of the invention.

Optimally, the strong force interaction of deuterium nuclei which areanharmonically oscillating occurs in the host lattice with a high degreeof coherency. The more non-linear, or anharmonic, the deuteriumsub-lattice behaves, the higher the coherency of the anharmonicoscillations. Condensed matter systems in which the deuteron nucleimotions are synchronized to such a high degree are expected to generallytend toward conditions that favor 3- and 4-body strong forceinteractions. Such many-bodied, cooperative oscillations permit 3 nucleito be confined in, or close to, the strong force envelopesimultaneously, providing a corresponding increase in interactionpotential. Prediction of reaction by-products of 3- and 4-body strongforce interactions are beyond current understanding. High energyscattering experiments are of no predictive use, owing to theimmeasurably low probability of even a 3-body interaction.

It must also be recognized that the anharmonic tunneling oscillationsdescribed herein occur in a space regime such that the inertialwavelength of the deuterons is much greater than that typicallyassociated with high-energy events. Thus, substantial overlap of thewave-functions of nearby nuclei, even those outside of the interactionenvelope of a nuclei pair, can be expected. Additionally, interferenceeffects of the low-energy tunneling oscillations can not be dismissed.Indeed, the energy of the deuterated palladium silver system is computedto be seven orders of magnitude lower than the lowest energy scatteringexperiments (≈20,000 eV compared with 20 meV). Conversely, the deBrogliewavelength of a wave/particle deuteron is increased by √107 over that ofscatter high energy experiments. Thus, interference effects of thetunneling phenomena can not be discounted.

Anharmonic oscillations resulting from specific molecular orbitaldegeneracy may be understood from another viewpoint. The amplitude, δ,of the anharmonic oscillations may be equated with the energy of theoscillating system. The energy of the oscillator thereby correlates awavelength with the oscillating particle. When the wavelength, λ, of ananharmonically oscillating deuteron coincides with the length of apotential well, here the Coulomb barrier, a resonance is expected.Tuning of the anharmonicity of a condensed matter system thus acts toadjust the wavelength of the wave/particle entity (here, the deuteron)to induce particular resonances. The induced resonance further enhancesthe oscillation amplitude, δ, and can dramatically increase theprobability of a strong force interaction between neighboring nuclei.

The inventors herein have recognized that in addition to preciselyselecting an alloy host lattice for enhancing anharmonicity of guestdeuterium nuclei, the application of an electric field may be employedto shift the HOMO and LUMO populations and energy spectra of a givenhost lattice to achieve molecular orbital degeneracy and enhancedanharmonicity. It is recognized, however, that E-fields are confined tothe near-surface region of conducting materials. Therefore, E-fieldsonly control the system anharmonicity in a region of the system whosedepth is less than about 200 Å-deep into the bulk of a host material.Additionally, the inventors herein have recognized a third mechanism fortuning the degeneracy and anharmonicity of a system, namely, usingnanometric surface preparation (NSP) techniques on the host lattice.Such preparation is intended to impart nanoscale surface topology to thehost lattice; this topology acts to create a low coordination of thesurface atoms. Surfaces with a low coordination of atoms developanharmonic properties owing to orbital de-localization at regions ofhigh curvature, where the radius of curvature of such regions isgenerally less than 0.2 μm. Nanometric surface preparation, like theapplication of E-fields, is confined to effect only the surface and nearsurface regions of a host lattice. Each of these anharmonicity tuningmechanisms will be described in tun below.

Electric fields, which are limited to the near surface of a metal, makesubstantial changes to the local force constants and accompanyingvibrational response of near-surface atoms of a metal. Anharmonicoscillations driven by molecular orbital degeneracy are modified by theapplications of electric fields, mediated by the local adjustments tothe force constants. However, these effects are distributed over theinteraction distance of the anharmonic potentials, which may extendnormal to the surface over many lattice parameters.

As described below it is intended that a "tuned" degenerate host latticebe charged, via electrolysis, to populate interstitial sites withdeuterium. The strong electric fields developed during such electrolysisis recognized to provide two effects, based on an understanding of thesystem: a strong E-field insures that a high concentration of deuterium(or other guest species) is obtained and maintained within the lattice;and a strong E-field provides a driving force to further delocalize theD(1s) orbitals of the host lattice nuclei, beyond that resulting from aparticular selection of host alloy. Fields on the order of 10⁴ -10⁷Volts/cm occur within and at the surface of conducting materialsundergoing electrolysis, extending normal to the surface on the order ofnanometers, The exact quantification of the effect of an E-field on thesurface can not be made at this time. However, Hellman-Feynman theorysuggests that the E-fields act on the population of electron molecularorbitals, which action can be systematically employed to shift the Fermienergy in a direction leading to further degeneracy, for the properE-field polarity. Of course, the E-field may detract from a particularorbital population as well, depending on the E-field polarity; hence itis appropriate to consider the application of an E-field as degeneracytuning.

Consider Pd.sub..77 Ag.sub..23 D, discussed above as providing a highdegree of enhanced deuterium anharmonicity and a rate of deuteriumnuclei interaction of 7×10⁻²⁷ interactions/D--D pair/sec. Theapplication of an electric field to this system during, e.g.,electrolysis, further delocalizes the already degenerate molecularorbitals by an additional 5-10%, resulting in an increase of theanharmonic oscillation amplitude, δ, of the deuterium nuclei by anadditional 0.1 Å beyond the 0.6 Å oscillation amplitude caused by theanharmonic conditions of the Pd.sub..77 Ag.sub..23 D alloy latticealone. In this case, the barrier penetration parameter, or averagedistance of closest approach, of two deuterium nuclei, is then 0.5 Å,and the rate of deuterium nuclei strong force interactions increasesfrom 7×10⁻²⁷ interactions/D--D pair/sec to 4.6×10⁻¹⁰ interactions/D--Dpair/sec. Thus, the application of an E-field, e.g., duringelectrolysis, increases the interaction rate by seventeen orders ofmagnitude. As explained previously, the nature of these interactions isnot here specified; rather, chemical and physical conditions thatpromote the occurrence of these interactions are provided by theenhanced anharmonicity system of the invention.

For the majority of materials having properties which lend them as ahost lattice, and particularly for nickel and nickel alloys, theanharmonicity tuning mechanisms of E-field applications and nanometricsurface preparation do not present a hinderance to system performance,because ideal heat transfer favors a surface phenomenon, and thesemechanisms promote anharmonicity at the surface, rather than the bulk ofthe material.

The third anharmonicity tuning mechanism of the invention, nanometricsurface preparation (NSP), acts to adjust the local coordination ofsurface atoms, as explained above. High curvature surfaces, such asprismatic edges and asperities, are optimal low atomic coordinationsurfaces, and may be fabricated with existing technology to create ahigh density of such features with nanometric curvature radii of lessthan 0.2 μm. The new atomic coordinations produced by the resultingsurface topology induce variations in electron molecular orbitalsexpected of atoms of a smooth surface; these electron molecular orbitalshave different size, shape, orientation and, perhaps most importantly,population than those associated with a smooth surface. The newmolecular orbital occupancy levels associated with this lower atomiccoordination tend to shift the Fermi level such that the degeneracy ofthe system is increased, and the anharmonicity of the system iscorrespondingly increased. Additionally, NSP surfaces enhance thedissolution of hydrogen isotopes in a host lattice during electrolysis,thereby promoting population of tetrahedral sites in the host lattice.

Considered in another way, partitioning of a highly nonlinear, i.e.,anharmonic, solid such as the Pd.sub..77 Ag.sub..23 D alloy so that thealloy is nanometrically discretized, using, for example, NSP methods ofthe invention, leads to enormous vibrational instabilities in the solid,and correspondingly large vibration spectra. That is, atomic scalediscreteness effects give rise to localized vibrational states thatwould not exist in a continuum, nondiscretized system. It is theselocalized vibrational states that provide the large amplitudeanharmonicity recognized by the inventors herein as the foundation forenhancing nuclear interaction between nearest neighbor guest species ina host lattice. The existence and quantification of the correlationbetween nanometric partitioning and vibrational instabilities isprovided by, for example, Dauzois and Peyard, "Energy Localization inNonlinear Lattices," Physical Review Letters, Vol. 70, No. 25, Jun. 21,1993, pp. 3935-3938; and Kivshar and Peyard, "Modulational instabilitiesin discrete lattices," Physics Review A, Vol. 46, No. 6, Sep. 15, 1992,p. 3198.

Several host lattice surface preparation techniques are preferred toproduce this effect, but those skilled in the art will recognize thatother techniques are equally applicable to achieve the desired increasein anharmonicity. These techniques can be classified into twocategories: first, post-processing techniques, such as wire drawing,nanoscribing, lithography, and back-etching, and secondly, materialssynthesis techniques, such as CVD, MBE, ED,or PVD over articulatedsurfaces, surface coatings, and selective binary compound etching, allof which are described below.

In a first technique for providing nanoscopic topology to the surface ofa host lattice material, the host lattice material, in the form of wire,is drawn through a diamond die which has been processed to includerelief topology. Such a topology is achieved on a diamond die bypositioning a high-power laser, for example, a CO₂ or YAG laser,focussed to a spot size of less than 30 μm, at sufficient power toablate diamond, to locally evaporate carbon on the inside radial surfaceof the die. The laser is focused to a desired diameter spot size, whichis preferably not more than 30 μm, and either raster scanned ormodulated in a pulsed fashion along the inner wall of the diamond die.

This rastering or pulsing action results in the effective "drilling" ofbevelled holes in the diamond die. Pulsed laser sources, as opposed tocontinuous wave sources, provide the most flexibility for "customizing"the imparted relief topology. By selectively programming the rasteringand dwell time of the laser as it is applied to the inner wall of adiamond die, the inner wall surface of the die may be sculptured in apredefined way to provide bevelled features. The resulting features maybe smoothed with a laser annealing step or subsequent diamond pastepolishing step to remove rough spots on the interior of the holes.Preferably, in this application, the diamond die is processed tointentionally impart nanometric and microscopic features into thetrailing edge, i.e., smallest diameter, of the die.

In an alternative technique, a diamond abrasive, in the form of a paste,may be applied to a diamond die to provide topology on the inner surfaceof the die by scoring that surface as the paste is passed through thedie.

Once a diamond die is processed to include on its inner surfacenanometric-sized bevelled features or scored asperities, host latticewire, e.g., nickel or palladium wire, is drawn through the die. Afterbeing drawn through the die, the wire will take on the relief structureof the die; handling care is called for to avoid post-process roundingof the nanometrically sharp features on the drawn wire. Indeed,conventional wire drawing technology is designed to minimize topologicalfeatures on drawn wire, and thus, typically includes a surface polishingstep. Such a polishing step is disadvantageous for this process.

Specific preferable steps of the wire drawing process are as follows.Prior to being drawn through a prepared diamond die, the wire to beprocessed is cleaned via a series of solvent washes, for example: wash(1)--15 minute immersion in 40° C. trichloroethane with ultrasonicagitation; wash (2)--15 minute immersion in fresh 40° C. trichloroethanewith ultrasonic agitation; wash (3)--15 minute immersion inroom-temperature acetone with ultrasonic agitation; wash (4)--15 minuteimmersion in room-temperature methanol with ultrasonic agitation; wash(5)--15 minute immersion in room-temperature isopropanol with ultrasonicagitation; and final wash (6)--30 minute rinse in distilled water. Afterthis cleaning process, the wire is drawn through the die while beinglubricated. A suitable lubricant is selected based on the need to avoidorganic contamination of the alloy surface.

In an alternate embodiment, multi-clad wire of nickel and palladium maybe fabricated to provide enhanced anharmonicity due to both a specificalloy combination and surface topology. Referring to FIG. 3A, suchmulti-clad wire is fabricated using a solid, cylindrical copper rod 10,a solid, cylindrical nickel rod 12 of a diameter less than the diameterof the copper rod, and a palladium sheet 14 having a length equal tothat of the copper and nickel rods. The length and diameters of the rodsare determined based on the desired final length and diameter of themulti-clad wire to be produced. In a first fabrication step, shown inFIG. 3B, the copper rod 10 is machined to remove copper from theinterior of the rod, thereby creating a copper tube. The inner diameter16 of the copper tube is preferably machined to match the diameter of acylindrical assembly 18 comprising the nickel rod 12 around which iswrapped the palladium sheet 14. In a next step, shown in FIG. 3C, thenickel rod-palladium sheet assembly 18 is pressed into the copper tube10 to form a billet. As shown in FIG. 3D, a copper cap 20 having acentrally located hole is then welded to one end of the billet and apumping lead. 22 is attached to the cap hole.

The pumping lead 22 is connected to a vacuum system and the billet isevacuated via the system for approximately 12 hours at a temperature of300° C. At the end of the evacuation period, the pumping lead 22 isweld-sealed to isolate the billet from atmosphere, and the assembly iscooled to room temperature. Once the billet is cooled, it is extruded,using conventional extruding techniques, to have an outside diameter ofnot more than 2 inches. Then, using a group of successively smallerdies, the extruded billet (now a wire) is drawn through the dies fromlargest die to smallest, in sequence, to reach a final desired diameter.After the final die drawing, the copper cladding tube is etched off ofthe palladium sheet to expose the palladium-nickel assembly. A solutionof Hf/HNO₃ at room temperature, using standard etching and rinsingtechniques, adequately removes the copper and cleans the palladiumsurface. The resulting multi-clad wire may be used as is oralternatively, the wire may be drawn through a diamond die havingsurface features on its inner walls, using the process described above,to form the desired surface asperities on the wire.

In an alternative embodiment, an arbitrarily-shaped host latticematerial piece may be mechanically processed to create a planar surfacehaving nanometric topology using a lapping process as follows. If thepiece is rather small, it is first mounted on a quartz optical fiatusing a low-melting point temperature wax. The optical fiat is firstpositioned on a hot plate at approximately 90° C. The temperature of theoptical fiat is then increased until a small portion of wax melts on thefiat, at which point the rectangular piece is positioned on the meltedwax. The optical fiat, now supporting the rectangular sample, is thenremoved from the hot plate and cooled to room temperature.

The host lattice sample alone, or a supported smaller sample ispositioned on a nylon lapping pad of a standard lapping plate on apolishing wheel. A polishing slurry consisting of standard soluble 5 μmdiamond oil paste and mineral kerosine is loaded on the wheel tolubricate the sample during the lapping process. With the lubricatedsample in place, the wheel is run for about 30 minutes, throughout whichtime the lubrication is maintained.

At the end of the 30 minute-lapping period, the nylon lapping pad isreplaced with a new pad and the sample is positioned on the pad andlubricated with standard 2 μm diamond oil paste and mineral kerosine.The wheel is then run again for 30 minutes. In a third lapping process,the nylon pad is again replaced and the sample is run on the wheel for45 minutes using 0.5 μm diamond oil paste and mineral kerosine as thelapping lubricant. Finally, in a fourth lapping process, the nylon padis again replaced and the sample is run on the wheel for 2 hours using0.1 μm diamond oil paste and mineral kerosine as the lapping lubricant.This last lapping process using diamond paste imparts the desirednanometric features on the planarized surface.

If the arbitrarily-shaped host lattice sample was of such a small sizethat it was mounted on an optical fiat, the sample is removed from theflat, after the last lapping process, by melting the wax on the fiatusing a hot plate and removing the sample from the melted wax. Whetheror not an optical fiat support was employed, the sample is preferablycleaned at the end of the lapping procedure, following the multistagesolvent cleaning process described above in connection with the wiredrawing procedure, or other suitable cleaning procedure.

Alternative mechanical processing techniques may be employed to producenanometric surface topology for enhancing condensed anharmonicityaccording to the teachings of the invention herein. For example, in onemethod according to the invention, a diamond stylus is used tomechanically scribe the surface of a host lattice material in apredetermined scribe pattern. The diamond stylus is preferably"ultrasharp" in that the effective working tip diameter of the stylus isof nanometric proportions, and can thereby produce nanometric-sizedscribe patterns. The stylus is precisely moved across the surface of thematerial using a computer-controlled actuating mechanism. Such a systemand methods for using the system to produce nanometric scribe patternsare disclosed in U.S. patent application Ser. No. 929,341, entitled"Method and apparatus for forming nanometric features on surfaces,"filed on Sep. 13, 1992, by Harry Clark et al., and herein incorporatedby reference. An extension of this diamond stylus patterning techniqueemploys a stylus fixture having an array of such diamond tips which eachare characterized by nanometic-sized tip radii. The array of tipsprovides the ability to in tandem scribe many patterns across thesurface.

Using such a system, scratched relief topology is imparted to thesurface of, e.g., a sheet of host lattice material. It is not requiredthat the original surface topology of the sheet be planar, but rather,the topology may even be slowly undulating. Active sensors, for example,or other means of the computer-controlled actuating mechanism permit anarray of styli to ride lightly on the surface, no matter its topology,and additionally, restrict the depth of cut to, e.g., less than 2 μm. Inthis way, a large surface area can be processed in an acceptable timeperiod. As described below, such a nanometrically processed sheet may beused in its initial form as a sheet or may be wound into a small spatialvolume, to form a coiled tube, much in the manner of an electrolyticcapacitor design.

According to a preferred embodiment of the invention herein, nanometricsurface features are produced using the diamond stylus scribing schemedescribed above, in combination with a "post-scribe" ultrasonic anodicetch process. The application of an E-field during the etching serves topopulate antibonding orbitals in the near surface of the host lattice,thereby facilitating decohesion of, typically, metallic bonds. Such ananodic etch is carried out using, e.g., a solution of hydrochloric aciddiluted with three parts water. A platinum electrode may be employed,for example. The anodic cell is operated under :reverse bias at severalmilliamps/cm² for a selected time period, such as 300 seconds,sufficient to produce a high density of nanoscale features on thesurface of the host lattice material. Ultrasonic agitation of the anodicetch bath promotes feature formation. The two-step scribe-anodic etchprocess produces a high density of nanoscale features on any size hostlattice sheet.

There are still other materials processing techniques that result insurfaces with sub-microscopic features. For example, diamond turning,fly cutting, and milling techniques are suitable for creating surfacestructures. Alternatively, various metallurgical techniques may beemployed; suitable metallurgical methods include the process ofco-solidification of a binary mixture with low solubility in the solidphase. The resulting solidified matrix will have dendritic (needle-like)filaments in the midst of the second phase element. Selective etching ofthe second phase element results in a porous, spongy material with highcurvature surfaces. Ni--Al and Pd--B are two examples of relativelyinsoluble metal systems that are preferred for this technique. Vapordeposition techniques that are customized to favor discontinuous, ratherthan smooth and continuous deposition characteristics result insub-micron sized nucleation sites that enhance the anharmonicity of theunderlying substrate surface. Conversely, vapor deposition of a smoothcoating over a highly textured surface achieves this same result ofsub-micron sized asperities. An example of this process is theautoclaving of open-cell polystyrene. The decomposition resulting fromthe autoclaving produces a carbonaceous skeleton with very small featuresizes.

Chemical vapor deposition (CVD) is a molecular level process whereby twomolecules react only when conjoined on a hot surface. This thermallyactivated process is thus useful in producing a selected surfacetopology, because the two or more molecular species employed in theprocess do not react in the gas phase. Deposition onto a heatedsubstrate can be precisely controlled with adjustments to thetemperature of the substrate, as well as the relative composition of thegas phase constituents.

For this application, deposition quality and thickness are best obtainedat low pressures, an operating regime providing the ability to producevery thin layers. This is especially true for an articulated surface,such as a pyrolized organic foam. Coating the interior regions of such asurface is referred to as chemical vapor infiltration (CVI). Clearly,ultrathin coatings are preferred for this application, lest the smallpores of the foam plug up and obstruct the nanometric surfacereactivity.

Whatever mechanical technique is chosen for imparting sub-micron sizedsurface features to a material surface, that technique should optimallyprovide a high density of surface asperities, which preferably includepoints, prisms, and corners, or comprise any geometries having featureswith a radius of curvature less than 0.5 μm, but preferably less than0.2 μm. Such features provide a location 29 of small radius curvature.Geometries having a radius of curvature more than 0.2 μm will enhanceanharmonicity to some extent, but to a lesser degree than smallercurvature surface features.

While nanometric surface features, as described above, have been shownto be effective in enhancing anharmonicity, techniques of the inventionherein for discetization of metallic grain size at nanometric dimensionsalso provides the ability to promote enhanced anharmonicity. Based onprior work by Peyrad, et al., "Energy Localization in NonlinearLattices," Physical Review Letters, Vol. 70, no. 25, p. 3935, 1993, itis known that energy localization occurs in one-dimensional nonlinearlattices. The inventors herein have recognized that in three dimensions,discrete nanodots or nanocrystals of anharmonic metals can develop largeamplitude oscillations resulting from quantum size effects. Rather thandamping large oscillations, nonlinear nanodot structures favor thegrowth of large amplitude, low frequency anharmonic latticeoscillations. Such intrinsically localized vibrational states augmentthe anharmonicity enhancement provided by the schemes described aboveand provide a mechanism for sustaining resonant dynamic Jahn-Telleroscillations.

Such resonant oscillations are only to be expected to be observable inmaterials that have in some way been partitioned or discretized. Incontrast to the expected material behavior, partitioning of condensedmatter on a nanoscale relaxes the assumption of equi-partitioning ofenergy. Thus, local modes of vibration that would normally decay in aharmonic lattice spontaneously grow in amplitude in a nonlinear,anharmonic lattice. These massive, but localized oscillations do notfollow classical continuum mechanics principles.

For example, it has been shown by Suryanarayana, in "The Structure andMechanical Properties of Metallic Nanocrystals," Metallurgical Trans. A,Vol. 23, p. 1074, 1992, that materials with ultrafine grain dimensionsare characterized by extremely high diffusion rates. Such high diffusionrates provide the ability to diffuse a guest species, e.g., a hydrogenisotope such as deuterium, in a host lattice, e.g., nickel or apalladium silver alloy, to a high ratio.

There are many materials processing techniques within the scope of theinvention for introducing resonant anharmonic oscillations into a guestspecies of a host lattice. Grain boundaries, stacking faults, freesurfaces and abrupt compositional variations are materials structuresthat discretize or partition condensed matter to develop the vibrationalinstabilities that are recognized by the inventors herein to promotenuclei interaction. The simplest such method is grain refinement, whichmay be produced via splat cooling, atomization, selective depositiontechniques, and cold working. Cold working by mechanical attrition hasbeen shown to provide nanograined, polycrystalline material compositionby Koch, in "The Synthesis and Structure of Nan, crystalline MaterialsProduced by Mechanical Attrition," Nanostructured Materials, Vol. 2, p.109, 1993.

Cold working or work hardening tends to result in metal morphology thatis brittle and prone to fracture. Such fracture, i.e., large cracking,of surfaces is to be avoided here because an electric field applied tosuch a cracked surface would not penetrate into cracks and fissures. Asa result, dissolved guest hydrogen isotopes in a host lattice would havean available path to be reemitted from the host material, therebypreventing the ability to attain a high guest to host ratio. Thus,optimization of grain size must be balanced against tendency of agrained material to fracture. Annealing is not a viable techniquebecause it causes grain growth.

As an alternative to mechanical and metallurgical techniques forproducing nanometric surface features, lithographic wet-etch techniquesmay be used. For example, referring to FIG. 4A, in a first lithographicprocess, a bare substrate 30 of a selected host lattice material, forexample, nickel, is provided with a selected crystallographicorientation, for example, the 110 or 100 orientation. The 110 crystalfaces are favored in the case of a nickel host lattice substrate becausethe 110 planes support the highest solubility of hydrogen isotopes ofany crystallographic planes.

As shown in FIGS. 4B, 4C and 4D, photoresist 32 is spun on the substrateand exposed using a patterned lithographic mask 34 having a selectedpattern of sub-micron sized geometries. Preferably, the maximum patterndimension, d, or "duty cycle" of repeated pattern is about 0.2 μm inlength. Such nanoscale features require the use of thin, state of theart photoresists. The unexposed resist is then removed using standardtechniques to produce a photoresist etch mask. As shown in FIGS. 4E and4F, the underlying substrate is then anisotropically etched using anappropriate etch to produce grooves in the substrate surface having adepth, h, of less than about 1 μm. Grooves of a greater height are lesspreferable because they would allow the prismatic faces of groovesexceeding about 1 μm to reconstruct to a more harmonic, high atomiccoordination state. After removing the resist etch mask using standardphotoresist processing techniques, the substrate 30 is provided with atopology of steps 36 which all ideally exhibit sharp corners andstraight walls.

In a second lithographic process, shown in FIGS. 5A-5F, a bare substrate30 oriented in a preferred crystallographic orientation of [100] hasphotoresist spun on its surface. The resist is then exposed using a maskhaving a maximum pattern width, d, of 1 μm in a grid pattern. Theunexposed resist is removed using standard resist process techniques andthe substrate is preferentially etched through openings in the remainingphotoresist etch mask. The preferential etch stops on the 111crystallographic planes of the substrate lattice, which act as etch stopplanes and cause the etch to end at the intersection of the 111 planeswithin the substrate.

At the completion of the etch and after the removal of the photoresistetch mask using standard photoresist process techniques, the substratesurface comprises a pattern of grooves 38 having sharp points at thepeak of the groove and a correspondingly reverse pointed indentationinto the substrate surface. As explained in the discussion earlier,these grooves act to produce a low coordination of surface atoms, andconsequently, to increase the anharmonicity of the hydrogen or hydrogenisotope dissolved in the surface material. It is intended thatalternative lithographic techniques may also be employed to createsuitable surface topology structures which enhance the anharmonicity ofthe surface material.

The inventors herein have found that mechanically derived surfacenanofeatures manifest a different set of properties thanlithographically etched features. By their nature, etch processes attackthe most reactive regions of a surface preferentially over the lessreactive regions. The less reactive regions are then, in turn, what isleft exposed at the end of the etch process. These exposed regions aregenerally characterized by localized molecular orbitals. In contrast,mechanical processes, as opposed to etch processes, do not selectivelymodify surface regions of particular reactivity, thereby retaining theoriginal surface reactivity, to a large extent.

However, wet-chemistry techniques, such as electroplating andchromatography, also provide mechanisms for creating finely dispersednanometric structures on the surface of a material to enhance thematerial anharmonicity. For example, in one method according to theinvention, enhanced anharmonicity of a material is achieved usingnanometric-sized particles of a second material to promote selectedsurface geometry via a process such as electroplating the material ofinterest. In one scheme, nanometric particles such as fullerenes arecoated with 3-20 atomic layers of a selected host lattice material, suchas Ni, Ti, Pd, Zr, or their alloys discussed above. In this scheme, thediameter of the coated fullerene (C₆₀)-material coating combination isbetween 10-30 Å. The outer metal atomic layers have such a lowcoordination of atoms in this geometry that the outermost electronmolecular orbitals of the layers de-localize and enhance theanharmonicity of the metal layer at its surface. To be useful, coatedparticles such as metalized fullerenes must be distributed in some inertmedia, such as xeolites or carbonaceous devitrified foams. The inertmedia serves two functions: it provides a support structure for thefullerenes, and it accommodates suspension of each C₆₀ Fullerene ballsuch that they each provide the entire 4πr² of active surface area perball. The inert media must be of a porous nature such that it ispermeable, so that the fullerene balls can be charged via, e.g., anelectrolyte, that provides the charging interstitial species, such ashydrogen, deuterium, or tritium.

In an alternative embodiment according to the invention, a superlatticeof alternating materials is produced to enhance anharmonicity of thealternating materials at each superlattice layer interface. In onescheme, alternating layers of two materials are created using molecularbeam epitaxy, organo-metallic chemical vapor deposition, evaporation,laser ablation, or sputtering techniques to fabricate a prespecifiedsuperlattice configuration. Ideally, these deposition and growthprocesses are highly controlled such that they produce high qualitysuperlattice structures having abrupt interfaces at each layer.Preferred material groups for the alternating superlattice layer pairsinclude Au--Ni, Cu--Pd, Cu--Ni, Ag--Pd, Ni--Pd, Cu--Ni, Ni--Ti, Zr--P,Pd--P, Ni--Zr, Zr--Pd, and Zr--Ti. Other layer material groups may alsobe suitable. The layer thicknesses preferably vary from about 1-30 nm,depending on the growth or deposition technique. At these small layerthicknesses, the interfacial regions where one material layer meets thenext are characterized by lattice distortion, altered atomiccoordinations and orbital de-localization. As explained in thediscussion above, these conditions promote an enhancement of thesystem's anharmonicity, and corresponding enhancement of nucleiinteraction rate.

Ion sputtering of metallic targets is perhaps the superlatticefabrication process most amenable to a large area processing scheme.Such large area processing is ideal for creating a host latticestructure of desired size. In this process, the substrate is placed is avacuum chamber, after which the chamber is evacuated. An ion beam isdirected at, for example, a Nickel target located in the chamber or withaccess to the chamber, and nickel vapors are deposited onto thesubstrate. To produce the superlattice, the ion beam is alternatelydirected at the nickel target and, for example, a copper target, for aprescribed amount of time sufficient to deposit alternating layers ofnickel and copper. Typical deposition times are based on a depositionrate of less than about 2 nanometers/minute. Based on this rate, asuperlattice of 30 Ni--Cu layers, each 2 nm-thick, may be processed inone hour. The temperature of the superlattice substrate is selected tomaximize the abruptness of each layer junction, keeping in mind that lowtemperature depositions reduce the amount of alloying at, for example,each Ni--Cu interface.

Superlattice structures so created enhance local anhamonic conditionsnot only at the external surface of the structures, but also at everyinterface in the superlattice array. Thus, for a 40-50 layersuperlattice, the active volume of less than about 5 μm in thicknessgenerates heat, due to anharmonicity effects on deuterium nucleiinteraction at each interface of the superlattice, that cannot betransferred away from the interface as effectively as heat generated atthe external surface of the superlattice. In this case, the interior ofthe lattice begins to "overheat" as the heat production via anharmonicinteractions exceed the thermal diffusivity of the lattice materials.Temperature does not strongly effect anharmonic oscillation, as it doesharmonic oscillation, but several hundred degrees Centigrade ofgenerated heat may be sufficient to initiate a static Jahn-Tellerdistortion that results in quenching anharmonic oscillations.

Still other surface processing techniques are intended by the inventionherein. For example, ion implantation of, for example, Cr into Ni,creates surface damage of the Nickel and provides a mechanism forproducing the desired atomic delocalization.

Referring to FIG. 6, there is shown an experimental setup 40 forproducing and measuring the effect of enhanced anharmonicity on theinteraction of guest sublattice nuclei dissolved in a host lattice. Thissetup 40 comprises, for example, an interaction cell 45, which ismonitored to provide indicative signals via a pressure line 47, acurrent line 48, a radiation line 50, and a voltage line 52. Each ofthese signal lines are provided to an analog to digital converter (A/D)54, which is connected to a PC 56, provided with a display 580

As shown in FIG. 7, the interaction cell 45 consists of, for example, a30 liter Pyrex calorimetry vessel 46 containing heavy water, lightwater, or a suitable mixture of the two, and a suitable electrolyte,such as 0.6 Molar potassium carbonate (K₂ CO₃) 48 in which are submergedelectrodes 50, 52, described below. Nonwater-based electrolyticsolutions may also be suitable. The containment vessel 46 servesprimarily to contain the electrolyte and not decompose contaminationinto electrodes submerged within it. The electrolyte provides a sourceof protons or deuterons without contaminating the surface of theelectrodes. It also serves to establish a high double potential justoutside the surface of the electrodes that provides a voltage gradientwhich shifts the dynamic equilibrium of solvation and favors a highdensity of protons or deuterons in the solid, once such speciesdissolves in the solid, as explained below. The volume of electrolyte isof secondary importance. Heat transfer mechanisms are the main purposeof the water. Water is excellent in this capacity because it ischemically stable, inflammable, and has a large specific heat. Otherelectrolytes may be used. The electrical conductivity as well as thepolarizability of the electrolyte may be preferably optimized for agiven type of electrode material. For example, NaCO₃ or RbCO₃ may beused.

Also submerged in the liquid within the containment vessel are twothermocouples 54, 56, for determining the temperature in the liquid andthe air above the liquid, respectively, within the vessel. Each of thethermocouples is monitored by suitable apparatus, such as the PC 56 ofthe experimental setup.

The containment vessel 46 is provided with a teflon lid (not shown),which is to be loosely mounted on the vessel once the vesselconfiguration is in place. The looseness of the mounting is intended toallow pressure release during operation such that no hazardous pressurebuild-up occurs within the vessel. Additionally, a pressure relief valve58 may be provided on the vessel lid. The lid also provides for thepressure line mentioned above, and sensing lines for a gauge, forexample, a Bourdon gauge, and a radiation detector 50. The radiationdetector may be mounted either inside or outside the vessel, orpreferable, one detector is mounted inside while a second detector ismounted outside of the vessel. The detector located inside the vesselmay be located, for example, very dose to the electrode 50. One suitabledetector (for Tritium) is the Bicron Industries Corp. scintillationdetector.

A programmable DC power supply 62 is connected to the electrodes 50, 52within the vessel via corresponding connections 66, 64, in aconfiguration as given below. The electrodes within the vessel comprisea cathode 50 and an anode 52. The cathode 50 consists of, for example, aperforated teflon spacer 68 having an 8-inch diameter, around which iswound a suitable host lattice material, such as nickel wire 70, or otherselected material. A suitable amount of nickel wire is approximately2-20 pounds of wire.

Such nickel wire 70 might comprise 0.003" nickel-200 wire. Thiscommercially available wire is composed of >98.5% nickel, with smallamounts of iron and cobalt. The wire may be treated with any of thesurface topology processes described above to enhance the anharmonicityof the wire system. For example, the wire may be pulled through alaser-treated diamond die (as described above) such that surface reliefstructures on the die impart corresponding nanometric topologicalstructures on the wire surface. The wire may be loosely braided into acable of 125 strands, or some other braid scheme. The cable is wrappedloosely around the teflon spacer such that a maximum amount of wiresurface area is exposed. The braiding scheme also provides the abilityto increase the surface area for a given amount of wire material. Othercathode wire and material alternatives are also suitable. The wrappedspacer 68 is entirely submerged in the liquid 48 within the containmentvessel. From its location in the vessel, the cathode 50, comprising thespacer 68 and wire 70, is connected to the negative line 66 of the powersupply 62 via a spot-welded solid nickel rod 72, or other connectingline. This rod is thick enough to carry a high current density withoutoverheating a connecting fitting 74 in the vessel lid.

In an alternate cathode configuration, a scintillation material isplated with nickel and attached to the cathode configuration 50described above. This configuration provides a radiation detectormechanism in intimate contact with host lattice material, and may beconnected to the radiation detector line 50 described above.

In a further alternative cathode configuration (not shown), a sheet ofplanar nickel or palladium alloy NSP processed as described above via,e.g. diamond scribing and anisotropic etching, is used in its sheet formas a cathode, or alternatively, rolled in a manner like that ofelectrolytic capacitors, forming a coiled tube which provides a largecathode surface area within a comparatively small volume. Such a cathodeconfiguration, like the others, is entirely submerged in the liquidwithin a containment vessel. The rolled structure is particularlyefficient in that it allows the liquid to deliver the protons ordeuterons while at the same time providing a surface cooling mechanismvia flushing of the liquid across the cathode surface.

Referring to FIG. 8, the anode 52 is shown in more detail. The anodeconsists of, for example, a cage 76 of chemically inert metal, such astitanium or nickel, which is plated with 0.0005" platinum. The cagediameter is 6" and the cage height is 6". Such a cage is made of top andbottom metal tings 78, 80, respectively, connected between which aremetal fins 82, each fin having the dimensions of 0.030" in thickness and5/8" in width. A number of such fins, five for example, are spot-weldedto the top and bottom tings 78, 80. The particularly chosen size andnumber of fins is based on the amount of the cathode material used.Without an adequate anode surface size, the operation of the cell set-upmay become current limited. The top ring 78 is also spot-welded to a1/8" nickel rod 84 for connection to the positive line 64 of the powersupply 62.

In operation, the power supply is set to provide a voltage drop of notless than 0.5 volts below the hydrogen overvoltage of 1.43 V forwardbiased between the anode and cathode. Electrolysis proceeds during thevoltage application to dissolve a large ratio of hydrogen isotope, e.g.,deuterium, into the host lattice; ideally a guest-host ratio of greaterthan 0.8 is achieved via the electrolysis.

As discussed above, nanoscale features on the host lattice, e.g., thenickel wire surface, enhance the transport of deuterium into the nickelsurface and thereby promote such a high loading ratio. Furtherenhancement is provided using a chopped DC voltage rather than aconstant DC voltage. The use of this signal scheme is motivated asfollows. Maintenance of a high guest loading ratio requires a strongelectric field gradient at the host surface. However, unintentionalimpurities in the electrolytic cell may hinder the existence of thisgradient; such impurities in the cell invariably transport to thesurface of the cathode, where they deposit on the cathode host surface.The impurities generally establish a polarization layer on the surfacethat reduces the effectiveness of the E-field there. This is due to thenature of the polarization layers responding in a capacitive manner;that is, the transport of charge across the polarization layer decaysunder the application of a constant DC field, as would be expected tooccur across capacitor plates. Thus, such polarization layers act as anopen circuit to an applied constant DC voltage. Accordingly, it ispreferred that an AC voltage component be superimposed on a quiescent DCvoltage to sustain transport across any polarization layers; suchcapacitive polarization layers act as a short circuit, rather than anopen circuit, to the AC component.

The applied voltage is thus preferred to be a positive DC voltage with aduty cycle of between 5-2000 Hz, e.g., a square wave signal with apositive DC offset voltage, and an amplitude switching no less than 0.5V below the hydrogen overvoltage of 1.43 V. With such a voltage scheme,the near surface of the host cathode acts like a diode, magnifyingcharge transport in the forward bias mode and restricting transport ofdissolved guest species back out of the surface. In chemical terms, theDC chopping voltage acts to shift the dynamic equilibrium to a statefavoring higher concentrations of guest species.

The current density of the operating cell is determined based on thecell's operating environment; the current density of the cathode hostmaterial is preferably not more than 100 μ/cm². Given a requirement tokeep the power density to a reasonable level, and considering the factthat the anharmonicity enhancement techniques of the invention aresurface phenomenon, the power density is minimized via a cathode designproviding an increase in surface to volume ratio of the cathode. Forexample, the cathode host material may be fabricated, as describedabove, as large, thin sheets, and then the two electrodes may beinterleaved with anode structures wound in parallel with the cathode ina design like that of an electrolytic capacitor. In such a design, theelectrode sheets are ideally fabricated thinly, for example, as thin as0.001", separated by a distance of 0.025". This separation distance isprovided by some insulating media, e.g., even the liquid itself. Heatresulting from the operation of such an anode-cathode configuration inthe ,operating cell electrolyte is transferred via cycling of theelectrolyte through the cylindrical volume.

During cell operation, the electrolyte temperature is operated at aselected point for optimizing transport of heat from the electrodes. Forexample, the electrolyte may be maintained at or near its boiling pointbecause this phase change can transport energy at a constanttemperature.

Operation of a cell in the manner described above provides optimizationof the materials and system for enhancing anharmonic oscillations of thesystem and correspondingly enhancing the probability for interaction ofnuclei within the lattice. As discussed above, the methods of theinvention taught herein for producing this enhancement are all based onrecognition by the inventors herein that nanometric discretization ofhighly nonlinear materials produces large localized vibrationalinstabilities, giving rise to large-amplitude oscillation of nucleiwithin the material. Such oscillation provides a correspondingenhancement of the potential for nuclei in the material to interact.

Other embodiments, features, and processing methods are intended withinthe scope of the invention, as defined by the claims.

We claim:
 1. Apparatus for producing dynamic anharmonic oscillations ofa condensed matter guest species comprising:a condensed matter hostlattice having surfaces upon at least a portion of which are providedsurface features, said features having a radius of curvature less than0.5 microns, and means for dissolving said guest species in said hostlattice in a ratio of at least 0.5, the guest species undergoing saiddynamic anharmonic oscillations upon dissolution in said host lattice.2. The apparatus of claim 1 wherein said guest species is dissolved insaid host lattice in a ratio of at least 0.8.
 3. The apparatus of claim1, wherein the host lattice comprises palladium.
 4. The apparatus ofclaim 1, wherein the host lattice comprises an alloy of palladiumsilver.
 5. The apparatus of claim 1, wherein the host lattice comprisesthe palladium silver alloy Pd.sub..77 Ag.sub..23.
 6. The apparatus ofclaim 1, wherein the host lattice comprises nickel.
 7. The apparatus ofany of claims 3, 4, 5, or 6, wherein the guest species compriseshydrogen.
 8. The apparatus of any of claims 3, 4, 5, or 6, wherein theguest species comprises deuterium.
 9. The apparatus of claim 1 whereinthe means for dissolving said guest species comprises a container for anelectrolytic solution containing said guest species.
 10. The apparatusof claim 9 wherein the condensed matter host lattice comprises apalladium silver alloy cathode, and the means for dissolving said guestspecies farther comprises:a platinum-coated anode, a support for thecathode such that the cathode is submerged when in the electrolyticsolution, and a support for the anode such that the anode is submergedwhen in the electrolytic solution.
 11. The apparatus of claim 10 whereinthe cathode comprises a sheet of palladium silver alloy rolled to form acoil tube of said sheet.
 12. The apparatus of claim 9 wherein thecondensed matter host lattice comprises a cathode, and the means fordissolving said guest species further comprises:an anode, a support forthe cathode such that the cathode is submerged when in the electrolyticsolution, and a support for the anode such that the anode is submergedwhen in the electrolytic solution.
 13. The apparatus of claim 12 whereinthe cathode comprises a wire.
 14. The apparatus of either of claims 11or 13 wherein the anode comprises at least one platinum-coated wire. 15.The apparatus of either of claims 11 or 12 wherein the electrolyticsolution comprises a solution of heavy water and K₂ CO₃.
 16. Theapparatus of either of claims 11 or 12 wherein the electrolytic solutioncomprises a solution of light water and K₂ CO₃.